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[Sandia Lab News]

Vol. 53, No. 15        July 27, 2001
[Sandia National Laboratories]

Albuquerque, New Mexico 87185-0165    ||   Livermore, California 94550-0969
Tonopah, Nevada; Nevada Test Site; Amarillo, Texas

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Sandians win R&D 100 Awards Labs works on risk-informed regulation for NRC Rep. Heather Wilson on balanced energy


Sandia researchers win three R&D 100 Awards

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By Chris Burroughs

Three Sandia research teams -- one from New Mexico and two from California -- have won R&D 100 Awards in the annual competition for innovative technology sponsored by R&D Magazine, a trade magazine based in the Chicago area.

Teams of technical experts chosen by the magazine select 100 winners of the annual contest. The winners must not only be original but also show promise of real-world application.

Prizes in the form of plaques will be presented at a banquet hosted in October by the magazine at Chicago's Museum of Science and Industry.

The Sandia winners invented an Ion Electron Emission Microscope, polymer hydrogen getters, and a new process for growing compound semiconductors of cadmium-zinc-telluride for room temperature radiation detection.

"Sandia's R&D 100 winners this year represent those fundamental advances in technology that are so essential for making progress in other fields," says Labs President and Director C. Paul Robinson of the awards. "All three awards represent new inventions, and all three make significant strides in extending the state of the art, but at the same time each is extremely cost-effective over past methods.

"Developing such 'systems solutions' is what we have been emphasizing as Sandia's reason for being, and it is very rewarding to see the R&D 100 Awards honor the work. I am also pleased that two of the three awards included team members from industry and universities. Technology partnerships are also a major thrust, and these awards indicate just what is possible through such teaming efforts."

Summaries of the winning technologies follow:

Ion Electron Emission Microscope

The Ion Electron Emission Microscope (IEEM), invented by New Mexico-based researchers Barney Doyle and George Vizkelethy (both 1111), Robert Weller of Vanderbilt University, and Berthold Senftinger of Staib Instruments Inc. in Germany, is the first device that allows scientists and engineers to microscopically study the effects of single ions on semiconductors, integrated circuits, and biological specimens without having to focus the MeV ion beam. The IEEM nomination was submitted jointly by Sandia and Staib, the company currently manufacturing the microscope.

Barney says that unlike earlier microscopy systems, one version of the IEEM -- the alpha-source IEEM -- doesn't even use an accelerator.

"It replaces a building full of expensive accelerator and nuclear microfocusing equipment with a device the size of a scanning electron microscope," Barney says. "It will also be a fraction of the cost of a conventional nuclear microprobe."

The low cost and size comes at no reduction in capability and even enables for the first time some experiments using accelerators, which were previously considered unsuitable for nuclear microscopy.

Barney speculates that this development "could well lead to a renaissance in nuclear microscopy, particularly for studying electron transport in semiconductors and microelectronics and for radiobiology research."

Instead of focusing high-energy ions like the Hybrid Nuclear Microscopy System (Lab News, Sept. 22, 2000), which has been the standard form of locating problem areas in radiation-hardened integrated circuits for the past decade, the IEEM technique determines the position where an individual ion enters the surface of the sample by projection secondary electron emission. These position signals are then correlated with the ion-induced signal generated in the sample or device under test.

The IEEM comes in two forms, one using a particle accelerator, and one using a radioactive alpha particle source.

"The main advantage of the accelerator-IEEM over commercial focused beam nuclear microprobes is the low-cost and small size, even after it is integrated into a beam," he says. "The IEEM system will also allow us to perform Radiation Effects Microscopy using the highly ionizing beams from the Radio Frequency Quadrupole linac booster recently added to the tandem accelerator in the Ion Beam Materials Research Lab in Bldg. 884.

"For the alpha-IEEM, future prospects are equally exciting because no accelerator is required -- just an alpha-particle source deposited on the objective aperture. The cost for the complete system is $100,000, compared to the multimillion dollar system for focused microbeams, which require accelerators," Barney says.

Polymer Hydrogen Getters

Tim Shepodd (8722), co-inventor of the polymer hydrogen getters (Lab News, May 5, 2000), calls the product the "greatest advance in getters in 50 years."

The getters permanently and irreversibly remove unwanted hydrogen and, as a result, can prevent explosions caused by hydrogen mixing with the atmosphere in sealed consumer products and avert hydrogen buildup that can result in a decrease of insulation properties or loss of efficiency in evacuated heat exchangers.

Tim and LeRoy Whinnery (8722) of Sandia/California are receiving the R&D 100 award for inventing the polymer hydrogen getters.

"Our getters allow the safe use of sealed, battery-operated devices such as flashlights, dive-lights, toys, and cameras without the risk of inadvertent detonation," Tim says.

It is long known that alkali and carbon/zinc batteries give off hydrogen. In unsealed devices, the hydrogen poses little danger because it is rapidly diffused. Batteries in sealed devices, however, easily yield sufficient hydrogen to create an atmosphere if over-drained, charged, or inverted.

The polymer hydrogen getters function in two ways. They either scavenge hydrogen with carbon-carbon multiple bonds, or, when oxygen is present, safely make water through recombination. The Sandia getters are customized for each customer, made from readily available ingredients, nonhazardous, and designed to remove hydrogen in a variety of atmospheres, including vacuum, inert, air, or steam.

"Polymer hydrogen getters are a spectacular example of an enabling technology," Tim says. "They are deployed as a small, passive part of numerous technologies and are usually less than one percent of the mass and cost. Yet without getters, the entire technology may not be able to be safely or economically deployed. A flashlight that explodes, a camera that could malfunction or explode -- these consumer products are made safe by our technology."

Sandia's polymer hydrogen getters are currently marketed under a licensing agreement with Vacuum Energy Inc. of Cleveland, Ohio.

Solid-State Radiation Detectors

Detection and imaging of nuclear materials, such as radiotracers in nuclear medicine, just got easier. The reason is a new technique of growing large single crystals of cadmium zinc telluride (CZT) suitable for producing radiation detectors. The technique was developed by a team of researchers from Sandia/California; Yinnel-Tech Inc. in South Bend, Ind.; Techion -- Israel Institute of Technology; and Fisk University.

"Progress in the area of solid-state X-ray and gamma-ray detectors has been linked to producing better crystals. Our discovery of a technique to grow large single crystals of CZT with the desired electrical properties has begun to transform the technology area, creating new thrusts and directions for solid-state radiation sensors and imaging arrays," says Ralph James, who served as the Sandia principal investigator for the project. He left the Labs this spring to join Brookhaven National Laboratory as Associate Laboratory Director.

The solid-state radiation detectors based on semiconductor materials made from cadmium zinc telluride are unique because they can operate at room temperature, detect X- and gamma-ray radiation with high efficiency, and uniquely identify the isotopes responsible for the emitted radiation.

The team's development of an improved technique to grow detector-grade CZT crystals and a new method to reduce the dark current flowing along the crystal surfaces have allowed for major improvements in the signal-to-noise ratio, long-term stability, and yield of single-crystal material.

Ralph says the detectors have diverse applications, ranging from environmental cleanup, imaging of gamma-ray bursts, radiography, and safeguarding the world's inventory of nuclear materials to improved detection of tumors and heart disease.

Before the team developed the new technique, a detector capable of distinguishing natural background emanating from common building materials and the radiation characteristics of many isotopes relied on bulky equipment that had to be cooled to super-low temperatures and attended frequently by a technician. Preparing the equipment for use required precooling for a few hours.

Radiation detectors produced from these new materials need no cooling, are easy to use, require little or no maintenance, and provide the capability to identify radioactive sources in the field, Ralph says.

CZT detectors had been produced using other growth techniques, but the low yield of large-volume single crystals limited the detectors' efficiency and availability and led to costs that were prohibitively high for several applications. The cost reduction for large, single crystals of CZT has enabled a more widespread use, particularly for imaging applications.

Team members from Sandia included Eilene Cross (8517), Jay Erickson (former student intern), Richard Olsen (8724), Gomez Wright (former student intern), and Walter Yao (now at Advanced Micro Devices, Inc.). -- Chris Burroughs

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Sandia efforts may lead to safer, less expensive nuclear power plants

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By Chris Burroughs

Future US nuclear power plants might be safer, more efficient, and less expensive to build thanks to the efforts of several Sandians who are working with the US Nuclear Regulatory Commission (NRC) to develop new approaches for regulating reactors. This work is an extension of efforts to modify existing regulations for currently operating reactors.

Sandia, which has been doing probabilistic risk assessments (PRAs) for nuclear reactors for the NRC since the mid-1970s, is using that experience to help the agency revise decades-old regulations following a risk-informed regulatory approach.

Risk-informed regulation combines the results from PRAs with sound engineering practices to develop regulations that ensure a cost-effective approach to safety.

"The risk-informed approach allows the NRC to relax requirements that aren't important and focus on those that are," says Allen Camp, Manager of Risk, Reliability, and Modeling Group 6410. "After 20 years of research, we've gained a clearer understanding of how accidents begin and progress. We know better which requirements make a plant safe -- those that prevent or mitigate accidents -- and which ones don't."

The NRC has established goals stating that nuclear power plant operation should not expose the public to significant additional risk. PRAs have given the NRC considerable evidence to show that these goals are generally being met, indicating that nuclear energy continues to be a very safe method of generating electricity.

Over the years, PRAs have shown areas where the plants needed to be improved, and also areas where NRC regulations may require unwarranted conservatism.

Risk-informed alternatives

A risk-informed alternative to an existing regulation may eliminate or modify some requirements while imposing others. An important goal of risk-informed regulation is to use risk information to provide flexibility in plant operation and design, which can reduce construction and operating costs while enhancing safety.

In the early days of nuclear power plants -- and then even more so after the Three Mile Island accident -- the NRC regulations became extremely prescriptive, building many safety layers into the plant design. For example, the Three Mile Island accident raised concerns about the potential for ignition of hydrogen gas generated during an accident.

To address this concern, the NRC imposed new requirements to help prevent hydrogen combustion from becoming a problem in an operating plant. Later analyses showed that some power plant designs did not need all of these requirements.

"It wasn't unusual for plant operators to spend training time preparing for a variety of extremely unlikely accidents instead of events that pose a much more real threat to the public," Allen says. "This is completely counter to safety."

Tom Sanders, Manager of Nuclear Initiatives Dept. 6406, says the NRC turned to Sandia to assist with risk-informed alternatives to regulations because of "its experience in risk assessment and severe accident analysis for nuclear power plants."

Unrealistic conservatism?

Over the past two decades, Labs personnel have visited many plants and built an understanding of their operations as part of nuclear power risk assessment activities. Sandia provides a unique perspective to the NRC on how the regulations affect nuclear power safety.

"The Labs' role has been helping the NRC to figure out which parts of the regulations must stay, and which ones can be modified, and how to modify them,' Tom says.

For example, Sandia is currently involved in identifying risk-informed alternatives to the regulations for emergency core cooling.

Emergency core cooling systems provide cooling water in a light water reactor in the event of a pipe break of other loss of coolant accident. Current regulations, which were developed in the early 1970s, require these systems to begin delivering water within seconds of a large pipe break, and to prevent core damage despite major failures within the system.

More recent risk information has shown several ways in which the methods used to evaluate these systems were unrealistically conservative. Reducing these conservatisms allows for more realistic training and testing of equipment, thus enhancing safety. According to Jeff LaChance (6410), changing these regulations could save the nuclear industry, and thus consumers of electricity, $1 billion or more because plants could operate at increased power levels even while reducing operating costs.

Current NRC regulations

The current NRC regulations were developed for light water reactors, such as those now in operation in the US. However, Sandia is working to bring the same risk-informed approaches to regulating advanced reactor designs being developed by the nuclear industry and DOE.

Risk-informed approaches have an even greater potential for savings in advanced reactors, because significant improvements can be made in the initial designs.

Sandia is supporting DOE's Nuclear Energy Research Initiative as part of an industry/university/national laboratory team to develop risk-informed approaches for advanced designs.

The NRC is now preparing to regulate advanced reactor designs. Several companies have approached the NRC about the certification and licensing of new reactor designs.

Exelon Generation Co. is considering an application for a site permit during 2002, and several additional site permit applications are expected to follow. The type of reactor Exelon plans is a pebble bed modular reactor (PBMR) -- as opposed to the light water reactor. Licensing for the PBMR will involve the use of risk information to adapt the current regulatory process to their design.

"Because no pebble bed reactors have ever been built in the US, the NRC does not have regulations to govern their design, construction, and operation," says Greg Wyss (6410). "While the first PBMR license will probably use a modified version of the current regulations, the NRC will likely develop completely new regulations for future reactors. And Sandia will help guide them in a risk-informed approach."

Given the initial successes of risk-informed regulation with the NRC, Sandia sees the potential for many other applications of these approaches, Tom says. Essentially any regulated industry or operation can make use of these ideas. For example, the new risk-informed regulations may include guidelines for recycling waste from the nuclear fuel cycle. Assessment of proliferation risk and development of related regulatory guidelines may also be possible.

Allen says the changes to the NRC regulatory process are proceeding and major changes for future reactors will happen over the next few years.

"The technical basis for this approach has been developed, and the NRC continues to be a leader among federal agencies in implementing risk-informed processes," Allen says.< -- Chris Burroughs

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Rep. Wilson thanks Sandians for energy work; calls for balanced approach to energy policy<

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By Bill Murphy

Rep. Heather Wilson, R-N.M., came to Sandia last week to say "thanks" to Labs employees for the work they've done over the years to help build America's energy security and to talk to Sandians, community leaders, and news reporters about the need for a balanced national energy policy.

Her visit to Sandia's National Solar Thermal Test Facility was part of a coordinated nationwide "day of energy awareness" on July 16. The day was organized by Vice President Dick Cheney, who conducted an energy-related town hall meeting in Philadelphia. In addition to Wilson, at least 25 other GOP members of Congress held similar sessions in districts across the country.

Wilson said emphatically that the US House of Representatives will pass a national energy plan this year, one that takes a balanced approach to energy issues.

"We have a serious energy problem [in the US]," she said, adding that the issue long ago should have been given more attention by policymakers. "The silver lining of problems," she added, "is that they cause people to focus."

Recently, Wilson helped pass a bipartisan national energy plan in the House Energy and Air Quality Subcommittee. The bill includes provisions on energy conservation, renewable energy, clean coal technology, nuclear energy production, and advances in hydropower production.

In a Wilson-introduced amendment to the bill, the national laboratories will conduct a national assessment of renewable energy resources. Wilson also sponsored amendments to extend federal renewable R&D and strengthen nuclear energy programs.

In recent months, Wilson has emerged as a key Republican representative on energy policy matters. She was named by House GOP leadership to the 20-member House Energy Action Team (HEAT), which spearheads energy legislation in the US House of Representatives. She is a member of the House Energy and Commerce Committee, which has jurisdiction over energy policy. Wilson is a close political ally of Sen. Pete Domenici, R-N.M., widely recognized as one of the nation's key champions for nuclear energy and for a vibrant role for Sandia and other national labs in energy R&D.

Indeed, during her visit to Sandia, Wilson said she expects that Sandia's long record of involvement with energy research "will be even stronger in the years ahead."

Wilson spoke about the need for the nation to take a new look at nuclear energy, which has been the stepchild of the energy industry for most of a generation.

"It's time to re-think our position," she said. "Nuclear energy is safe, it's reliable, and it can help us reduce our reliance on foreign sources of energy."

Wilson spelled out what she views as "the bottom line" regarding energy supply in the US.

We want an energy policy, she said, that "allows us to flip a switch and have the lights come on. We want a gasoline supply where the prices are not exorbitant. . . and we want an energy supply that allows us to enjoy and protect our environment.

"We can achieve these goals with a balanced long-term approach," she said.

Prior to her comments, Wilson heard Sandia President Paul Robinson note that Sandia is "the total energy portfolio laboratory," with a history of work in fossil fuel R&D, conservation, renewables, nuclear energy, and supply surety.

Sandia chief economist Arnie Baker (6002) shared with Wilson a computer model tool, PowerSim, that allows the user to see the relationship between energy supply policy decisions and greenhouse gases. The software, while robust enough to be a useful learning tool, is compact enough to run on a laptop PC.

Sandia Energy Div. 6000 VP Bob Eagan welcomed Wilson "on behalf of the 900 people at Sandia who work in energy," providing her with an overview of some of the many research areas his division is involved in.

Following her remarks, Wilson received more detailed briefings from a number of Sandians about specific energy-related projects. -- Bill Murphy

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Last modified: July 26, 2001


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